The full list of attendees was undisclosed, but sources told Politico that both Zuckerberg and Google chairman Eric Schmidt were slated to attend. Yahoo CEO Marissa Mayer was also invited to attend, but she wasn't able to make the trip on such short notice, according to another source.

According to the following tweet, Zuckerberg was cutting it close, arriving just 6 minutes before the meeting was scheduled:

I spy Mark Zuckerberg of Facebook arriving outside the West Wing 6mins before a meeting with President Obama. pic.twitter.com/p72qGpcuYJ— Stephen Crowley (@Stcrow) March 21, 2014